In fiber optic telecommunication systems a carrier signal at a wavelength .lambda..sub.s is typically generated by a semiconductor laser. Information may be impressed on the carrier signal either by directly modulating the drive current to the laser or by externally modulating the light output of the laser. In contrast, systems are also contemplated in which fiber lasers, such as cladding pumped lasers (CPLs), provide the carrier signal. But, fiber lasers are optically pumped, and there is no known satisfactory technique for directly modulating them; an external modulator is the only practical approach at present, but even then may be limited to low power applications (e.g., less than about 200 mW for currently available lithium niobate modulators).
Thus, a need remains in the art for a fiber laser design which can be directly modulated.